Making medicine balls with liquid antibiotics?

You can use liquid medication just fine, but there shouldn't be a need to heat the peanut butter. If you really can't get it mixed in, then mix water in the peanut butter first until it's a mixable consistency. Then add your medication, and then flour to get the mixture to a texture where you can roll it.

I just mix liquid meds with nutella, they usually eat it ok.

I make oatmeal, mix in honey and the meds, and I haven't had a rat turn it down.

Here is what I've been doing for Zeeky.... I take a small bit of sugar cookie dough (Pillsbury) and roll it into a ball. (about the size of the tip of your finger) I then press it into a sort of bowl shape with my thumb. I then put the meds into the bowl and sprinkle a small amount of flour on top. Then using a small spoon I mix the flour and meds until they are a paste. Then I fold the whole thing in half and squish it up a bit and then roll it back into a ball. Zeeky eats it every time. I'm sure it's super high in calories, but I tried mixing it with a bunch of other stuff and he would refuse it or worse only eat part of it, which ruined the whole dose because I didn't know how much he actually got.

Thanks everyone!
I tried using PB and it mixed in well and formed easily into balls - they loved them and finished the whole ball, but I was biting my nails the whole time because the PB was sticky and they would gag a little at first as they were eating too fast. I think I'll probably try one of your methods instead so I don't have to worry about giving the ratty Heimlich.